Dr. Cheryl A. Gale is a neonatologist at the University of Minnesota. The candidate's long-term goal is to pursue an academic career devoted primarily to basic research. During Dr. Gale's pediatric residency and neonatal fellowship training, she was exposed to the high morbidity and mortality associated with systemic candidiasis in her premature patients on the neonatal intensive care unit. This experience solidified Dr. Gale's interest in understanding fungal pathogenesis as a means toward developing more effective therapies. The proposed application will provide the candidate the additional training necessary to be competitive for independent funding. The rich academic and research environment at the University of Minnesota is extremely well suited for the candidate's career development. Under the direct mentorship of Dr. Judith Berman, Dr. Gale will study the molecular mechanism of morphologic switching in C. albicans. She will focus on characterizing in vivo the localization of cytoskeletal-associated proteins during morphologic switching and determining the role of cell cycle checkpoints during morphogenesis. Morphologic switching is postulated to contribute to the success of C. albicans as a pathogen because it gives the fungus versatility in the face of changing environments. Dr. Gale previously found that the C. albicans gene INT1 encodes a protein that is important for the morphologic switch from yeast-form to filamentous-form. Expression of INT1 in the usually non- pathogepic yeast, S. cerevisiae, results in the formation of extremely elongated buds that appear similar to C. albicans germ tubes. Her more recent characterization of these elongated buds in S. cerevisiae has shown that Int1p expression causes a novel localization of cytoskeletal-associated proteins (septins) that mimics that of Int1p itself. She also found that INT1 expression results in a delay in the nuclear cell cycle partially due to the activation of the morphogenesis checkpoint protein, Swe1p. The Specific Aims of this proposal will build on these preliminary results to directly determine, in C. albicans, the role of Int1p, septins, and cell cycle checkpoints in morphologic switching. Dr. Gale will develop a technique of genomic epitope tagging in C. albicans that will allow in vivo localization of Int1p and septins in C. albicans during the cell cycle and during morphologic switching in both wild-type and mutant C. albicans morphologic strains (Specific Aims 1 and 2). The candidate will disrupt the C. albicans SWE1 homolog and study the effect of such a mutation on the viability and ability of the strain to undergo morphologic switching (Specific Aim 3). These studies will allow Dr. Gale to determine the how Int1p, septins and cell cycle control proteins are related in the process of morphologic switching and may identify new therapeutic targets for anti- fungal agents.